Hi,
I had the same problem. I realized that trying Firefox on a different computer worked fine (3 cols across). But on my main computer, I got 2 cols across.
I tried to access
https://www.zpz.cn/ but never got to a product layout, only to Chinese.
What fixed my system was to 'clear everything' in options -- and that cleared up my problem on my main PC -- but doesn't say others wouldn't run in to it.
You may want to try a test, and
1) either try using Firefox on another PC
2) clear all history as in attachment
While this is not something you could have a customer do, it may give you more information